| cell-to-cell movement of green fluorescent protein reveals post-phloem transport in the outer integument and identifies symplastic domains in arabidopsis seeds and embryos. | developing arabidopsis (arabidopsis thaliana) seeds and embryos represent a complex set of cell layers and tissues that mediate the transport and partitioning of carbohydrates, amino acids, hormones, and signaling molecules from the terminal end of the funicular phloem to and between these seed tissues and eventually to the growing embryo. this article provides a detailed analysis of the symplastic domains and the cell-to-cell connectivity from the end of the funiculus to the embryo, and within ... | 2005 | 16169962 |
| the arabidopsis r2r3 myb proteins four lips and myb88 restrict divisions late in the stomatal cell lineage. | the two guard cells of a stoma are produced by a single symmetric division just before terminal differentiation. recessive mutations in the four lips (flp) gene abnormally induce at least four guard cells in contact with one another. these pattern defects result from a persistence of precursor cell identity that leads to extra symmetric divisions at the end of the cell lineage. flp is likely to be required for the correct timing of the transition from cell cycling to terminal differentiation. fl ... | 2005 | 16155180 |
| an indole-3-acetic acid carboxyl methyltransferase regulates arabidopsis leaf development. | auxin is central to many aspects of plant development; accordingly, plants have evolved several mechanisms to regulate auxin levels, including de novo auxin biosynthesis, degradation, and conjugation to sugars and amino acids. here, we report the characterization of an arabidopsis thaliana mutant, iaa carboxyl methyltransferase1-dominant (iamt1-d), which displayed dramatic hyponastic leaf phenotypes caused by increased expression levels of the iamt1 gene. iamt1 encodes an indole-3-acetic acid (i ... | 2005 | 16169896 |
| the tomato aux/iaa transcription factor iaa9 is involved in fruit development and leaf morphogenesis. | auxin/indole-3-acetic acid (aux/iaa) proteins are transcriptional regulators that mediate many aspects of plant responses to auxin. while functions of most aux/iaas have been defined mainly by gain-of-function mutant alleles in arabidopsis thaliana, phenotypes associated with loss-of-function mutations have been scarce and subtle. we report here that the downregulation of iaa9, a tomato (solanum lycopersicum) gene from a distinct subfamily of aux/iaa genes, results in a pleiotropic phenotype, co ... | 2005 | 16126837 |
| the genes encoding arabidopsis orc subunits are e2f targets and the two orc1 genes are differently expressed in proliferating and endoreplicating cells. | initiation of eukaryotic dna replication depends on the function of pre-replication complexes (pre-rc), one of its key component being the six subunits origin recognition complex (orc). in spite of a significant degree of conservation among orc proteins from different eukaryotic sources, the regulation of their availability varies considerably in different model systems and cell types. here, we show that the six orc genes of arabidopsis thaliana are regulated at the transcriptional level during ... | 2005 | 16179646 |
| evidence that insertion of tomato ringspot nepovirus ntb-vpg protein in endoplasmic reticulum membranes is directed by two domains: a c-terminal transmembrane helix and an n-terminal amphipathic helix. | the ntb-vpg protein of tomato ringspot nepovirus is an integral membrane protein found in association with endoplasmic reticulum (er)-derived membranes active in virus replication. a transmembrane helix present in a hydrophobic region at the c terminus of the ntb domain was previously shown to traverse the membranes, resulting in the translocation of the vpg domain in the lumen. we have now conducted an in planta analysis of membrane-targeting domains within ntb-vpg using in-frame fusions to the ... | 2005 | 16140753 |
| tanmei/emb2757 encodes a wd repeat protein required for embryo development in arabidopsis. | we identified the arabidopsis (arabidopsis thaliana) tanmei/emb2757 (tan) mutation that causes defects in both embryo and seedling development. tan mutant embryos share many characteristics with the leafy cotyledon (lec) class of mutants in that they accumulate anthocyanin, are intolerant of desiccation, form trichomes on cotyledons, and have reduced accumulation of storage proteins and lipids. thus, tan functions both in the early and late phases of embryo development. moreover, the tan and lec ... | 2005 | 16113228 |
| novel cipk1-associated proteins in arabidopsis contain an evolutionarily conserved c-terminal region that mediates nuclear localization. | environmental stimuli, including light, pathogens, hormones, and abiotic stresses, elicit changes in the cytosolic ca(2+) signatures of plant cells. however, little is known about the molecular mechanisms by which plants sense and transmit the specific cytoplasmic ca(2+) signal into the nucleus, where gene regulation occurs to respond appropriately to the stress. in this study, we have identified two novel arabidopsis (arabidopsis thaliana) proteins specifically associated with calcineurin b-lik ... | 2005 | 16113215 |
| a plant-specific protein essential for blue-light-induced chloroplast movements. | in arabidopsis (arabidopsis thaliana), light-dependent chloroplast movements are induced by blue light. when exposed to low fluence rates of light, chloroplasts accumulate in periclinal layers perpendicular to the direction of light, presumably to optimize light absorption by exposing more chloroplast area to the light. under high light conditions, chloroplasts become positioned parallel to the incoming light in a response that can reduce exposure to light intensities that may damage the photosy ... | 2005 | 16113226 |
| differential expression of the arabidopsis cytochrome c genes cytc-1 and cytc-2. evidence for the involvement of tcp-domain protein-binding elements in anther- and meristem-specific expression of the cytc-1 gene. | the promoters of the arabidopsis (arabidopsis thaliana) cytochrome c genes, cytc-1 and cytc-2, were analyzed using plants transformed with fusions to the beta-glucuronidase coding sequence. histochemical staining of plants indicated that the cytc-1 promoter directs preferential expression in root and shoot meristems and in anthers. in turn, plants transformed with the cytc-2 promoter fusions showed preferential expression in vascular tissues of cotyledons, leaves, roots, and hypocotyls, and also ... | 2005 | 16113211 |
| a comprehensive analysis of the nadp-malic enzyme gene family of arabidopsis. | the arabidopsis (arabidopsis thaliana) genome contains four genes encoding putative nadp-malic enzymes (mes; atnadp-me1-me4). nadp-me4 is localized to plastids, whereas the other three isoforms do not possess any predicted organellar targeting sequence and are therefore expected to be cytosolic. the plant nadp-mes can be classified into four groups: groups i and ii comprising cytosolic and plastidic isoforms from dicots, respectively; group iii containing isoforms from monocots; and group iv com ... | 2005 | 16113210 |
| the critical role of arabidopsis electron-transfer flavoprotein:ubiquinone oxidoreductase during dark-induced starvation. | in mammals, electron-transfer flavoprotein:ubiquinone oxidoreductase (etfqo) and electron-transfer flavoprotein (etf) are functionally associated, and etf accepts electrons from at least nine mitochondrial matrix flavoprotein dehydrogenases and transfers them to ubiquinone in the inner mitochondrial membrane. in addition, the mammalian etf/etfqo system plays a key role in beta-oxidation of fatty acids and catabolism of amino acids and choline. by contrast, nothing is known of the function of etf ... | 2005 | 16055629 |
| the arabidopsis pot1 and pot2 proteins function in telomere length homeostasis and chromosome end protection. | pot1 (protection of telomeres 1) is a single-stranded telomere binding protein that is essential for chromosome end protection and telomere length homeostasis. arabidopsis encodes two pot1-like proteins, dubbed atpot1 and atpot2. here we show that telomeres in transgenic plants expressing a truncated atpot1 allele lacking the n-terminal oligonucleotide/oligosaccharide binding fold (p1deltan) are 1 to 1.5 kb shorter than in the wild type, suggesting that atpot1 contributes to the positive regulat ... | 2005 | 16107718 |
| comparative proteomics using 2-d gel electrophoresis and mass spectrometry as tools to dissect stimulons and regulons in bacteria with sequenced or partially sequenced genomes. | we propose two-dimensional gel electrophoresis (2-de) and mass spectrometry to define the protein components of regulons and stimulons in bacteria, including those organisms where genome sequencing is still in progress. the basic 2-de protocol allows high resolution and reproducibility and enables the direct comparison of hundreds or even thousands of proteins simultaneously. to identify proteins that comprise stimulons and regulons, peptide mass fingerprint (pmf) with matrix-assisted laser deso ... | 2005 | 16145578 |
| fhl is required for full phytochrome a signaling and shares overlapping functions with fhy1. | phytochrome a (phya) plays a primary role in initiating seedling de-etiolation and is the only plant photoreceptor known to be activated by far-red light (fr). the signaling intermediate fhy1 appears to either participate directly in relaying the phya signal or to positively regulate a critical signaling event(s) downstream of phya activation. here we identify a homolog of fhy1 named fhl (fhy1-like) as a novel signaling factor essential for complete responsiveness to phya. fhl possesses function ... | 2005 | 16045472 |
| osptf1, a novel transcription factor involved in tolerance to phosphate starvation in rice. | we report here on a novel transcription factor with a basic helix-loop-helix domain for tolerance to inorganic phosphate (pi) starvation in rice (oryza sativa). the gene is designated osptf1. the expression of osptf1 is pi starvation induced in roots while constitutively expressed in shoots, as shown by northern-blot analysis. overexpression of osptf1 enhanced tolerance to pi starvation in transgenic rice. tillering ability, root and shoot biomass, and phosphorus content of transgenic rice plant ... | 2005 | 16006597 |
| arabidopsis cyp51 mutant shows postembryonic seedling lethality associated with lack of membrane integrity. | cyp51 exists in all organisms that synthesize sterols de novo. plant cyp51 encodes an obtusifoliol 14alpha-demethylase involved in the postsqualene sterol biosynthetic pathway. according to the current gene annotation, the arabidopsis (arabidopsis thaliana) genome contains two putative cyp51 genes, cyp51a1 and cyp51a2. our studies revealed that cyp51a1 should be considered an expressed pseudogene. to study the functional importance of the cyp51a2 gene in plant growth and development, we isolated ... | 2005 | 16040657 |
| sec8, a subunit of the putative arabidopsis exocyst complex, facilitates pollen germination and competitive pollen tube growth. | the exocyst, a complex of eight proteins, contributes to the morphogenesis of polarized cells in a broad range of eukaryotes. in these organisms, the exocyst appears to facilitate vesicle docking at the plasma membrane during exocytosis. although we had identified orthologs for each of the eight exocyst components in arabidopsis (arabidopsis thaliana), no function has been demonstrated for any of them in plants. the gene encoding one exocyst component ortholog, atsec8, is expressed in pollen and ... | 2005 | 16040664 |
| analysis of the rice mutant dwarf and gladius leaf 1. aberrant katanin-mediated microtubule organization causes up-regulation of gibberellin biosynthetic genes independently of gibberellin signaling. | molecular genetic studies of plant dwarf mutants have indicated that gibberellin (ga) and brassinosteroid (br) are two major factors that determine plant height; dwarf mutants that are caused by other defects are relatively rare, especially in monocot species. here, we report a rice (oryza sativa) dwarf mutant, dwarf and gladius leaf 1 (dgl1), which exhibits only minimal response to ga and br. in addition to the dwarf phenotype, dgl1 produces leaves with abnormally rounded tip regions. positiona ... | 2005 | 16040652 |
| functional redundancy of atftsh metalloproteases in thylakoid membrane complexes. | ftsh is an atp-dependent metalloprotease found in bacteria, mitochondria, and plastids. arabidopsis (arabidopsis thaliana) contains 12 atftsh proteins, three in the mitochondrion and nine in the chloroplast. four of the chloroplast ftsh proteins are encoded by paired members of closely related genes (atftsh1 and 5, and atftsh2 and 8). we have previously reported that atftsh2 and 8 are interchangeable components of atftsh complexes in the thylakoid membrane. in this article, we show that the var1 ... | 2005 | 16040665 |
| functional analysis of the pyrimidine de novo synthesis pathway in solanaceous species. | pyrimidines are particularly important in dividing tissues as building blocks for nucleic acids, but they are equally important for many biochemical processes, including sucrose and cell wall polysaccharide metabolism. in recent years, the molecular organization of nucleotide biosynthesis in plants has been analyzed. here, we present a functional analysis of the pyrimidine de novo synthesis pathway. each step in the pathway was investigated using transgenic plants with reduced expression of the ... | 2005 | 16024685 |
| pyruvate decarboxylase provides growing pollen tubes with a competitive advantage in petunia. | rapid pollen tube growth places unique demands on energy production and biosynthetic capacity. the aim of this work is to understand how primary metabolism meets the demands of such rapid growth. aerobically grown pollen produce ethanol in large quantities. the ethanolic fermentation pathway consists of two committed enzymes: pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh). because adh mutations do not affect male gametophyte function, the obvious question is why pollen synthesize a ... | 2005 | 15994907 |
| slow walker1, essential for gametogenesis in arabidopsis, encodes a wd40 protein involved in 18s ribosomal rna biogenesis. | the progression of mitotic division cycles and synchronous development between and within the male and female reproductive organs are essential for plant sexual reproduction. little is known about the genetic control of the progression of mitotic cycles of the haploid genome during gametogenesis in higher plants. here, we report the phenotypic and molecular characterization of an arabidopsis thaliana mutant, slow walker1 (swa1), in which the progression of the mitotic division cycles of the fema ... | 2005 | 15980260 |
| irregular trichome branch1 in arabidopsis encodes a plant homolog of the actin-related protein2/3 complex activator scar/wave that regulates actin and microtubule organization. | the dynamic actin cytoskeleton is important for a myriad of cellular functions, including intracellular transport, cell division, and cell shape. an important regulator of actin polymerization is the actin-related protein2/3 (arp2/3) complex, which nucleates the polymerization of new actin filaments. in animals, scar/wave family members activate arp2/3 complex-dependent actin nucleation through interactions with abi1, nap1, pir121, and hscp300. mutations in the arabidopsis thaliana genes encodin ... | 2005 | 16006582 |
| regulation of wuschel transcription in the stem cell niche of the arabidopsis shoot meristem. | pluripotent stem cells are localized in specialized microenvironments, called stem cell niches, where signals from surrounding cells maintain their undifferentiated status. in the arabidopsis thaliana shoot meristem, the homeobox gene wuschel (wus) is expressed in the organizing center underneath the stem cells and integrates regulatory information from several pathways to define the boundaries of the stem cell niche. to investigate how these boundaries are precisely maintained within the prolif ... | 2005 | 15980263 |
| distinct roles of gigantea in promoting flowering and regulating circadian rhythms in arabidopsis. | the circadian clock acts as the timekeeping mechanism in photoperiodism. in arabidopsis thaliana, a circadian clock-controlled flowering pathway comprising the genes gigantea (gi), constans (co), and flowering locus t (ft) promotes flowering specifically under long days. within this pathway, gi regulates circadian rhythms and flowering and acts earlier in the hierarchy than co and ft, suggesting that gi might regulate flowering indirectly by affecting the control of circadian rhythms. we studied ... | 2005 | 16006578 |
| the rice brassinosteroid-deficient dwarf2 mutant, defective in the rice homolog of arabidopsis diminuto/dwarf1, is rescued by the endogenously accumulated alternative bioactive brassinosteroid, dolichosterone. | we have identified a rice (oryza sativa) brassinosteroid (br)-deficient mutant, br-deficient dwarf2 (brd2). the brd2 locus contains a single base deletion in the coding region of dim/dwf1, a homolog of arabidopsis thaliana diminuto/dwarf1 (dim/dwf1). introduction of the wild-type dim/dwf1 gene into brd2 restored the normal phenotype. overproduction and repression of dim/dwf1 resulted in contrasting phenotypes, with repressors mimicking the brd2 phenotype and overproducers having large stature wi ... | 2005 | 15994910 |
| a link between ethylene and auxin uncovered by the characterization of two root-specific ethylene-insensitive mutants in arabidopsis. | the plant hormone ethylene participates in the regulation of a variety of developmental processes and serves as a key mediator of plant responses to biotic and abiotic stress factors. the diversity of ethylene functions is achieved, at least in part, by combinatorial interactions with other hormonal signals. here, we show that ethylene-triggered inhibition of root growth, one of the classical effects of ethylene in arabidopsis thaliana seedlings, is mediated by the action of the weak ethylene in ... | 2005 | 15980261 |
| control of root cap formation by microrna-targeted auxin response factors in arabidopsis. | the plant root cap mediates the direction of root tip growth and protects internal cells. root cap cells are continuously produced from distal stem cells, and the phytohormone auxin provides position information for root distal organization. here, we identify the arabidopsis thaliana auxin response factors arf10 and arf16, targeted by microrna160 (mir160), as the controller of root cap cell formation. the pro(35s):mir160 plants, in which the expression of arf10 and arf16 is repressed, and the ar ... | 2005 | 16006581 |
| the putative rna-dependent rna polymerase rdr6 acts synergistically with asymmetric leaves1 and 2 to repress brevipedicellus and microrna165/166 in arabidopsis leaf development. | the arabidopsis thaliana asymmetric leaves1 (as1) and as2 genes are important for repressing class i knotted1-like homeobox (knox) genes and specifying leaf adaxial identity in leaf development. rna-dependent rna polymerases (rdrps) are critical for posttranscriptional and transcriptional gene silencing in eukaryotes; however, very little is known about their functions in plant development. here, we show that the arabidopsis rdr6 gene (also called sde1 and sgs2) that encodes a putative rdrp, tog ... | 2005 | 16006579 |
| nuclear localization signal peptides induce molecular delivery along microtubules. | many essential processes in eukaryotic cells depend on regulated molecular exchange between its two major compartments, the cytoplasm and the nucleus. in general, nuclear import of macromolecular complexes is dependent on specific peptide signals and their recognition by receptors that mediate translocation through the nuclear pores. here we address the question of how protein products bearing such nuclear localization signals arrive at the nuclear membrane before import, i.e., by simple diffusi ... | 2005 | 16040740 |
| increasing tolerance to ozone by elevating foliar ascorbic acid confers greater protection against ozone than increasing avoidance. | ascorbic acid (asc) is the most abundant antioxidant in plants and serves as a major contributor to the cell redox state. exposure to environmental ozone can cause significant damage to plants by imposing conditions of oxidative stress. we examined whether increasing the level of asc through enhanced asc recycling would limit the deleterious effects of environmental oxidative stress. plants overexpressing dehydroascorbate reductase (dhar), which results in an increase in the endogenous level of ... | 2005 | 15951482 |
| localized hormone fluxes and early haustorium development in the hemiparasitic plant triphysaria versicolor. | perhaps the most obvious phenotypes associated with chemical signaling between plants are manifested by parasitic species of orobanchaceae. the development of haustoria, invasive root structures that allow hemiparasitic plants to transition from autotrophic to heterotrophic growth, is rapid, highly synchronous, and readily observed in vitro. haustorium development is initiated in aseptic roots of the facultative parasite triphysaria versicolor when exposed to phenolic molecules associated with h ... | 2005 | 15965023 |
| antisense suppression of deoxyhypusine synthase in tomato delays fruit softening and alters growth and development. | the effects of suppressing deoxyhypusine synthase (dhs) have been examined in tomato (solanum lycopersicum cv uct5). dhs mediates the first of two sequential enzymatic reactions that activate eukaryotic translation initiation factor-5a (eif-5a) by converting a conserved lys to the unusual amino acid, deoxyhypusine. dhs protein levels were suppressed in transgenic plants by expressing the 3'-untranslated region of tomato dhs under regulation of the constitutive cauliflower mosaic virus promoter. ... | 2005 | 15951486 |
| molecular characterization of maize acetylcholinesterase: a novel enzyme family in the plant kingdom. | acetylcholinesterase (ache) has been increasingly recognized in plants by indirect evidence of its activity. here, we report purification and cloning of ache from maize (zea mays), thus providing to our knowledge the first direct evidence of the ache molecule in plants. ache was identified as a mixture of disulfide- and noncovalently linked 88-kd homodimers consisting of 42- to 44-kd polypeptides. the ache hydrolyzed acetylthiocholine and propyonylthiocholine, but not s-butyrylthiocholine, and t ... | 2005 | 15980188 |
| hos10 encodes an r2r3-type myb transcription factor essential for cold acclimation in plants. | we report the identification and characterization of an arabidopsis mutant, hos10-1 (for high expression of osmotically responsive genes), in which the expression of rd29a and other stress-responsive genes is activated to higher levels or more rapidly activated than in wild-type by low temperature, exogenous abscisic acid (aba), or salt stress (nacl). the hos10-1 plants are extremely sensitive to freezing temperatures, completely unable to acclimate to the cold, and are hypersensitive to nacl. i ... | 2005 | 15994234 |
| constitutively high expression of the histidine biosynthetic pathway contributes to nickel tolerance in hyperaccumulator plants. | plants that hyperaccumulate ni exhibit an exceptional degree of ni tolerance and the ability to translocate ni in large amounts from root to shoot. in hyperaccumulator plants in the genus alyssum, free his is an important ni binding ligand that increases in the xylem proportionately to root ni uptake. to determine the molecular basis of the his response and its contribution to ni tolerance, transcripts representing seven of the eight enzymes involved in his biosynthesis were investigated in the ... | 2005 | 15923352 |
| inhibition of de novo pyrimidine synthesis in growing potato tubers leads to a compensatory stimulation of the pyrimidine salvage pathway and a subsequent increase in biosynthetic performance. | pyrimidine nucleotides are of general importance for many aspects of cell function, but their role in the regulation of biosynthetic processes is still unclear. in this study, we investigate the influence of a decreased expression of ump synthase (umps), a key enzyme in the pathway of de novo pyrimidine synthesis, on biosynthetic processes in growing potato (solanum tuberosum) tubers. transgenic plants were generated expressing umps in the antisense orientation under the control of the tuber-spe ... | 2005 | 15951490 |
| cinnamyl alcohol dehydrogenase-c and -d are the primary genes involved in lignin biosynthesis in the floral stem of arabidopsis. | during lignin biosynthesis in angiosperms, coniferyl and sinapyl aldehydes are believed to be converted into their corresponding alcohols by cinnamyl alcohol dehydrogenase (cad) and by sinapyl alcohol dehydrogenase (sad), respectively. this work clearly shows that cad-c and cad-d act as the primary genes involved in lignin biosynthesis in the floral stem of arabidopsis thaliana by supplying both coniferyl and sinapyl alcohols. an arabidopsis cad double mutant (cad-c cad-d) resulted in a phenotyp ... | 2005 | 15937231 |
| the recessive epigenetic swellmap mutation affects the expression of two step ii splicing factors required for the transcription of the cell proliferation gene struwwelpeter and for the timing of cell cycle arrest in the arabidopsis leaf. | generally, cell division can be uncoupled from multicellular development, but more recent evidence suggests that cell cycle progression and arrest is coupled to organogenesis and growth. we describe a recessive mutant, swellmap (smp), with reduced organ size and cell number. this defect is partially compensated for by an increase in final cell size. the mutation causes a precocious arrest of cell proliferation in the organ primordium and possibly reduces the rate of cell division there. the muta ... | 2005 | 15937226 |
| a basic helix-loop-helix transcription factor in arabidopsis, myc2, acts as a repressor of blue light-mediated photomorphogenic growth. | the crosstalk of light signaling pathways with other signaling cascades has just started to be revealed. here, we report the identification and functional characterization of a z-box binding factor (zbf1) in light signaling pathways. arabidopsis thaliana zbf1 encodes atmyc2/jin1, a basic helix-loop-helix transcription factor, which has recently been shown to be involved in abscisic acid (aba), jasmonic acid (ja), and jasmonate-ethylene signaling pathways. we demonstrate that atmyc2 interacts wit ... | 2005 | 15923349 |
| phytochrome b in the mesophyll delays flowering by suppressing flowering locus t expression in arabidopsis vascular bundles. | light is one of the most important environmental factors that determine the timing of a plant's transition from the vegetative to reproductive, or flowering, phase. not only daylength but also the spectrum of light greatly affect flowering. the shade of nearby vegetation reduces the ratio of red to far-red light and can trigger shade avoidance responses, including stem elongation and the acceleration of flowering. phytochrome b (phyb) acts as a photoreceptor for this response. physiological stud ... | 2005 | 15965119 |
| the arabidopsis transcription factor myb12 is a flavonol-specific regulator of phenylpropanoid biosynthesis. | comprehensive functional data on plant r2r3-myb transcription factors is still scarce compared to the manifold of their occurrence. here, we identified the arabidopsis (arabidopsis thaliana) r2r3-myb transcription factor myb12 as a flavonol-specific activator of flavonoid biosynthesis. transient expression in arabidopsis protoplasts revealed a high degree of functional similarity between myb12 and the structurally closely related factor p from maize (zea mays). both displayed similar target gene ... | 2005 | 15923334 |
| cloning and functional characterization of a formin-like protein (atfh8) from arabidopsis. | the actin cytoskeleton is required for many cellular processes in plant cells. the nucleation process is the rate-limiting step for actin assembly. formins belong to a new class of conserved actin nucleator, which includes at least 2 formin homology domains, fh1 and fh2, which direct the assembly of unbranched actin filaments. the function of plant formins is quite poorly understood. here, we provide the first biochemical study of the function of conserved domains of a formin-like protein (atfh8 ... | 2005 | 15923338 |
| genome-wide identification of genes expressed in arabidopsis pistils specifically along the path of pollen tube growth. | plant reproductive development is dependent on successful pollen-pistil interactions. in crucifers, the pollen tube must breach the stigma surface and burrow through the extracellular matrix of the stigma epidermal cells and transmitting tract cells before reaching its ovule targets. the high degree of specificity in pollen-pistil interactions and the precision of directional pollen tube growth suggest that signals are continually being exchanged between pollen/pollen tubes and cells of the pist ... | 2005 | 15894741 |
| interaction between phosphate-starvation, sugar, and cytokinin signaling in arabidopsis and the roles of cytokinin receptors cre1/ahk4 and ahk3. | cytokinins control key processes during plant growth and development, and cytokinin receptors cytokinin response 1/wooden leg/arabidopsis histidine kinase 4 (cre1/wol/ahk4), ahk2, and ahk3 have been shown to play a crucial role in this control. the involvement of cytokinins in signaling the status of several nutrients, such as sugar, nitrogen, sulfur, and phosphate (pi), has also been highlighted, although the full physiological relevance of this role remains unclear. to gain further insights in ... | 2005 | 15923327 |
| starch-related alpha-glucan/water dikinase is involved in the cold-induced development of freezing tolerance in arabidopsis. | cold-induced soluble sugar accumulation enhances the degree of freezing tolerance in various cold-hardy plants including arabidopsis (arabidopsis thaliana), where soluble sugars accumulate in only a few hours at 2 degrees c. hence, along with photosynthesis, starch degradation might play a significant role in cold-induced sugar accumulation and enhanced freezing tolerance. starch-related alpha-glucan/water dikinase (ec 2.7.9.4), encoded by arabidopsis starch excess 1 (sex1), is hypothesized to r ... | 2005 | 15894744 |
| atpdr12 contributes to lead resistance in arabidopsis. | arabidopsis (arabidopsis thaliana) contains about 130 atp-binding cassette (abc) proteins, which are likely to contribute to the transport of diverse materials, including toxic substances. however, the substrates of abc transporters remain unknown in most cases. we tested which abc transporter is involved in detoxification of lead [pb(ii)]. among the many tested, we found that the message level of only atpdr12 increased in both shoots and roots of pb(ii)-treated arabidopsis, suggesting that it m ... | 2005 | 15923333 |
| plantacyanin plays a role in reproduction in arabidopsis. | plantacyanins belong to the phytocyanin family of blue copper proteins. in the arabidopsis (arabidopsis thaliana) genome, only one gene encodes plantacyanin. the t-dna-tagged mutant is a knockdown mutant that shows no visible phenotype. we used both promoter-beta-glucuronidase transgenic plants and immunolocalization to show that arabidopsis plantacyanin is expressed most highly in the inflorescence and, specifically, in the transmitting tract of the pistil. protein levels show a steep gradient ... | 2005 | 15908590 |
| identification of cis-elements that regulate gene expression during initiation of axillary bud outgrowth in arabidopsis. | growth regulation associated with dormancy is an essential element in plant life cycles. to reveal regulatory mechanisms of bud outgrowth, we analyzed transcriptomes of axillary shoots before and after main stem decapitation in arabidopsis (arabidopsis thaliana). we searched for any enriched motifs among the upstream regions of up-regulated and down-regulated genes after decapitation. the promoters of down-regulated genes were enriched for ttatcc motifs that resemble the sugar-repressive element ... | 2005 | 15908603 |
| analysis of a sugar response mutant of arabidopsis identified a novel b3 domain protein that functions as an active transcriptional repressor. | a recessive mutation hsi2 of arabidopsis (arabidopsis thaliana) expressing luciferase (luc) under control of a short promoter derived from a sweet potato (ipomoea batatas) sporamin gene (spo(min)luc) caused enhanced luc expression under both low- and high-sugar conditions, which was not due to increased level of abscisic acid. the hsi2 mutant contained a nonsense mutation in a gene encoding a protein with b3 dna-binding domain. hsi2 and two other arabidopsis proteins appear to constitute a novel ... | 2005 | 15894743 |
| immunopurification of polyribosomal complexes of arabidopsis for global analysis of gene expression. | immunoaffinity purification of polyribosomes (polysomes) from crude leaf extracts of arabidopsis (arabidopsis thaliana) was achieved with transgenic genotypes that overexpress a translational fusion of a ribosomal protein (rp) with a his(6)-flag dual epitope tag. in plants with a cauliflower mosaic virus 35s:hf-rpl18 transgene immunopurification with anti-flag agarose beads yielded 60-svedberg ribosomal subunits, intact 80-svedberg monosomes and polysomes. sucrose density gradient fractionation ... | 2005 | 15955926 |
| dual role for tomato heat shock protein 21: protecting photosystem ii from oxidative stress and promoting color changes during fruit maturation. | the tomato (lycopersicon esculentum) chloroplast small heat shock protein (shsp), hsp21, is induced by heat treatment in leaves, but also under normal growth conditions in developing fruits during the transition of chloroplasts to chromoplasts. we used transgenic tomato plants constitutively expressing hsp21 to study the role of the protein under stress conditions and during fruit maturation. although we did not find any effect for the transgene on photosystem ii (psii) thermotolerance, our resu ... | 2005 | 15879560 |
| localization of the microtubule end binding protein eb1 reveals alternative pathways of spindle development in arabidopsis suspension cells. | in a previous study on arabidopsis thaliana suspension cells transiently infected with the microtubule end binding protein ateb1a-green fluorescent protein (gfp), we reported that interphase microtubules grow from multiple sites dispersed over the cortex, with plus ends forming the characteristic comet-like pattern. in this study, ateb1a-gfp was used to study the transitions of microtubule arrays throughout the division cycle of cells lacking a defined centrosome. during division, the dispersed ... | 2005 | 15879559 |
| the cyclin-dependent kinase inhibitor krp2 controls the onset of the endoreduplication cycle during arabidopsis leaf development through inhibition of mitotic cdka;1 kinase complexes. | exit from the mitotic cell cycle and initiation of cell differentiation frequently coincides with the onset of endoreduplication, a modified cell cycle during which dna continues to be duplicated in the absence of mitosis. although the mitotic cell cycle and the endoreduplication cycle share much of the same machinery, the regulatory mechanisms controlling the transition between both cycles remain poorly understood. we show that the a-type cyclin-dependent kinase cdka;1 and its specific inhibito ... | 2005 | 15863515 |
| identification and functional analysis of in vivo phosphorylation sites of the arabidopsis brassinosteroid-insensitive1 receptor kinase. | brassinosteroids (brs) regulate multiple aspects of plant growth and development and require an active brassinosteroid-insensitive1 (bri1) and bri1-associated receptor kinase1 (bak1) for hormone perception and signal transduction. many animal receptor kinases exhibit ligand-dependent oligomerization followed by autophosphorylation and activation of the intracellular kinase domain. to determine if early events in br signaling share this mechanism, we used coimmunoprecipitation of epitope-tagged p ... | 2005 | 15894717 |
| aureusvirus p14 is an efficient rna silencing suppressor that binds double-stranded rnas without size specificity. | rna silencing is a conserved eukaryotic gene regulatory system in which sequence specificity is determined by small rnas. plant rna silencing also acts as an antiviral mechanism; therefore, viral infection requires expression of a silencing suppressor. the mechanism and the evolution of silencing suppression are still poorly understood. tombusvirus open reading frame (orf) 5-encoded p19 is a size-selective double-stranded rna (dsrna) binding protein that suppresses silencing by sequestering doub ... | 2005 | 15890960 |
| cell and plastid division are coordinated through the prereplication factor atcdt1. | the cell division cycle involves nuclear and cytoplasmic events, namely organelle multiplication and distribution between the daughter cells. until now, plastid and plant cell division have been considered as independent processes because they can be uncoupled. here, down-regulation of atcdt1a and atcdt1b, members of the prereplication complex, is shown to alter both nuclear dna replication and plastid division in arabidopsis thaliana. these data constitute molecular evidence for relationships b ... | 2005 | 15928083 |
| cellulose biosynthesis: current views and evolving concepts. | to outline the current state of knowledge and discuss the evolution of various viewpoints put forth to explain the mechanism of cellulose biosynthesis. * | 2005 | 15894551 |
| virus induction of heat shock protein 70 reflects a general response to protein accumulation in the plant cytosol. | different cytoplasmically replicating rna viruses were shown to induce a specific subset of heat-inducible heat shock protein 70 (hsp70) genes in arabidopsis (arabidopsis thaliana). to identify the inducing principle, a promoterreporter system was developed for the facile analysis of differentially responding arabidopsis hsp70 genes, by infiltration into nicotiana benthamiana leaves. through transient expression of individual viral cistrons or through deletion analysis of a viral replicon, we we ... | 2005 | 15805473 |
| why is golden rice golden (yellow) instead of red? | the endosperm of golden rice (oryza sativa) is yellow due to the accumulation of beta-carotene (provitamin a) and xanthophylls. the product of the two carotenoid biosynthesis transgenes used in golden rice, phytoene synthase (psy) and the bacterial carotene desaturase (crti), is lycopene, which has a red color. the absence of lycopene in golden rice shows that the pathway proceeds beyond the transgenic end point and thus that the endogenous pathway must also be acting. by using taqman real-time ... | 2005 | 15821145 |
| unique translation initiation at the second aug codon determines mitochondrial localization of the phage-type rna polymerases in the moss physcomitrella patens. | the nuclear genome of the moss physcomitrella patens contains two genes encoding phage-type rna polymerases (pprpot1 and pprpot2). each of the pprpot1 and pprpot2 transcripts possesses two in-frame aug codons at the 5' terminus that could act as a translational initiation site. observation of transient and stable physcomitrella transformants expressing the 5' terminus of each pprpot cdna fused with the green fluorescent protein gene suggested that both pprpot1 and pprpot2 are not translated from ... | 2005 | 15834007 |
| arabidopsis cbf3/dreb1a and abf3 in transgenic rice increased tolerance to abiotic stress without stunting growth. | rice (oryza sativa), a monocotyledonous plant that does not cold acclimate, has evolved differently from arabidopsis (arabidopsis thaliana), which cold acclimates. to understand the stress response of rice in comparison with that of arabidopsis, we developed transgenic rice plants that constitutively expressed cbf3/dreb1a (cbf3) and abf3, arabidopsis genes that function in abscisic acid-independent and abscisic acid-dependent stress-response pathways, respectively. cbf3 in transgenic rice elevat ... | 2005 | 15834008 |
| citrate secretion coupled with the modulation of soybean root tip under aluminum stress. up-regulation of transcription, translation, and threonine-oriented phosphorylation of plasma membrane h+-atpase. | the aluminum (al)-induced secretion of citrate has been regarded as an important mechanism for al resistance in soybean (glycine max). however, the mechanism of how al induces citrate secretion remains unclear. in this study, we investigated the regulatory role of plasma membrane h+-atpase on the al-induced secretion of citrate from soybean roots. experiments performed with plants grown in full nutrient solution showed that al-induced activity of plasma membrane h+-atpase paralleled secretion of ... | 2005 | 15834009 |
| the pivotal roles of the plant s-adenosylmethionine decarboxylase 5' untranslated leader sequence in regulation of gene expression at the transcriptional and posttranscriptional levels. | s-adenosylmethionine decarboxylase (samdc; ec 4.1.1.50) is a key rate-limiting enzyme located in the polyamine biosynthesis pathway. when compared with other organisms, the plant samdc genes possess some distinct features because they are devoid of introns in the main open reading frame (orf) but have an intron(s) in their 5' untranslated leader sequences, in which two overlapping tiny and small upstream orfs (uorfs) are present. our results show that the presence of the 5' leader sequence plays ... | 2005 | 15821146 |
| ethylene-regulated floral volatile synthesis in petunia corollas. | in many flowering plants, such as petunia (petunia x hybrida), ethylene produced in floral organs after pollination elicits a series of physiological and biochemical events, ultimately leading to senescence of petals and successful fertilization. here, we demonstrate, using transgenic ethylene insensitive (44568) and mitchell diploid petunias, that multiple components of emission of volatile organic compounds (vocs) are regulated by ethylene. expression of benzoic acid/salicylic acid carboxyl me ... | 2005 | 15849311 |
| molecular cloning of ga 2-oxidase3 from spinach and its ectopic expression in nicotiana sylvestris. | previous work has shown that 13-hydroxylated gibberellins (gas) are predominant in the long-day (ld) plant spinach (spinacia oleracea; ga53, ga44, ga19, ga20, ga1, ga8, and ga29). also present in spinach are 2-hydroxylated c20-gas: ga97, ga98, ga99, and ga110. levels of the most abundant ga, ga97, decreased when plants were transferred from short photoperiods (sd) to ld. when [14c]ga53 was fed to spinach plants, more ga53 was converted to ga97 in sd than in ld, and more radioactive ga20 was form ... | 2005 | 15821147 |
| a novel short-root gene encodes a glucosamine-6-phosphate acetyltransferase required for maintaining normal root cell shape in rice. | glycosylation is a posttranslational modification occurring in many secreted and membrane-associated proteins in eukaryotes. it plays important roles in both physiological and pathological processes. most of these protein modifications depend on udp-n-acetylglucosamine. in this study, a t-dna insertional rice (oryza sativa) mutant exhibiting a temperature-sensitive defect in root elongation was isolated. genetic and molecular analysis indicated that the mutated phenotype was caused by loss of fu ... | 2005 | 15849305 |
| odorant1 regulates fragrance biosynthesis in petunia flowers. | floral scent is important to plant reproduction because it attracts pollinators to the sexual organs. therefore, volatile emission is usually tuned to the foraging activity of the pollinators. in petunia hybrida, volatile benzenoids determine the floral aroma. although the pathways for benzenoid biosynthesis have been characterized, the enzymes involved are less well understood. how production and emission are regulated is unknown. by targeted transcriptome analyses, we identified odorant1 (odo1 ... | 2005 | 15805488 |
| the n-terminal domain of chlorophyllide a oxygenase confers protein instability in response to chlorophyll b accumulation in arabidopsis. | plants acclimate to variations in light intensity by changing the antenna size of photosystems. this acclimation allows them to undergo efficient photosynthesis and creates a protective strategy to minimize photodamage. chlorophyll b synthesis by chlorophyllide a oxygenase (cao) is a key regulatory step in the control of antenna size. recently, we found that higher plant caos consist of three domains (a, b, and c domains) and confirmed that the c domain possesses catalytic function. to investiga ... | 2005 | 15805480 |
| a two-edged role for the transposable element kiddo in the rice ubiquitin2 promoter. | miniature inverted repeat transposable elements (mites) are thought to be a driving force for genome evolution. although numerous mites are found associated with genes, little is known about their function in gene regulation. whereas the rice ubiquitin2 (rubq2) promoter in rice (oryza sativa) line ir24 contains two nested mites (kiddo and mdm1), that in line t309 has lost kiddo, providing an opportunity to understand the role of mites in promoter function. no difference in endogenous rubq2 trans ... | 2005 | 15805485 |
| ddm1 binds arabidopsis methyl-cpg binding domain proteins and affects their subnuclear localization. | methyl-cpg binding domain (mbd) proteins in arabidopsis thaliana bind in vitro methylated cpg sites. here, we aimed to characterize the binding properties of atmbds to chromatin in arabidopsis nuclei. by expressing in wild-type cells atmbds fused to green fluorescent protein (gfp), we showed that atmbd7 was evenly distributed at all chromocenters, whereas atmbd5 and 6 showed preference for two perinucleolar chromocenters adjacent to nucleolar organizing regions. atmbd2, previously shown to be in ... | 2005 | 15805479 |
| arabidopsis tic110 is essential for the assembly and function of the protein import machinery of plastids. | the translocon at the inner envelope membrane of chloroplasts (tic) plays a central role in plastid biogenesis by coordinating the sorting of nucleus-encoded preproteins across the inner membrane and coordinating the interactions of preproteins with the processing and folding machineries of the stroma. despite these activities, the precise roles of known tic proteins in translocation, sorting, and preprotein maturation have not been defined. in this report, we examine the in vivo function of a m ... | 2005 | 15829604 |
| crown rootless1, which is essential for crown root formation in rice, is a target of an auxin response factor in auxin signaling. | although the importance of auxin in root development is well known, the molecular mechanisms involved are still unknown. we characterized a rice (oryza sativa) mutant defective in crown root formation, crown rootless1 (crl1). the crl1 mutant showed additional auxin-related abnormal phenotypic traits in the roots, such as decreased lateral root number, auxin insensitivity in lateral root formation, and impaired root gravitropism, whereas no abnormal phenotypic traits were observed in aboveground ... | 2005 | 15829602 |
| microrna directs mrna cleavage of the transcription factor nac1 to downregulate auxin signals for arabidopsis lateral root development. | although several plant micrornas (mirnas) have been shown to play a role in plant development, no phenotype has yet been associated with a reduction or loss of expression of any plant mirna. arabidopsis thaliana mir164 was predicted to target five nam/ataf/cuc (nac) domain-encoding mrnas, including nac1, which transduces auxin signals for lateral root emergence. here, we show that mir164 guides the cleavage of endogenous and transgenic nac1 mrna, producing 3'-specific fragments. cleavage was blo ... | 2005 | 15829603 |
| microrna-directed regulation of arabidopsis auxin response factor17 is essential for proper development and modulates expression of early auxin response genes. | the phytohormone auxin plays critical roles during plant growth, many of which are mediated by the auxin response transcription factor (arf) family. micrornas (mirnas), endogenous 21-nucleotide riboregulators, target several mrnas implicated in auxin responses. mir160 targets arf10, arf16, and arf17, three of the 23 arabidopsis thaliana arf genes. here, we describe roles of mir160-directed arf17 posttranscriptional regulation. plants expressing a mirna-resistant version of arf17 have increased a ... | 2005 | 15829600 |
| complete genome sequence and in planta subcellular localization of maize fine streak virus proteins. | the genome of the nucleorhabdovirus maize fine streak virus (mfsv) consists of 13,782 nucleotides of nonsegmented, negative-sense, single-stranded rna. the antigenomic strand consisted of seven open reading frames (orfs), and transcripts of all orfs were detected in infected plants. orf1, orf6, and orf7 had significant similarities to the nucleocapsid protein (n), glycoprotein (g), and polymerase (l) genes of other rhabdoviruses, respectively, whereas the orf2, orf3, orf4, and orf5 proteins had ... | 2005 | 15827145 |
| a rho family gtpase controls actin dynamics and tip growth via two counteracting downstream pathways in pollen tubes. | tip growth in neuronal cells, plant cells, and fungal hyphae is known to require tip-localized rho gtpase, calcium, and filamentous actin (f-actin), but how they interact with each other is unclear. the pollen tube is an exciting model to study spatiotemporal regulation of tip growth and f-actin dynamics. an arabidopsis thaliana rho family gtpase, rop1, controls pollen tube growth by regulating apical f-actin dynamics. this paper shows that rop1 activates two counteracting pathways involving the ... | 2005 | 15824136 |
| heterotopic expression of mpf2 is the key to the evolution of the chinese lantern of physalis, a morphological novelty in solanaceae. | morphological novelties arise through changes in development, but the underlying causes of such changes are largely unknown. in the genus physalis, sepals resume growth after pollination to encapsulate the mature fruit, forming the "chinese lantern," a trait also termed inflated-calyx syndrome (ics). stmads16, which encodes a mads-box transcription factor, is expressed only in vegetative tissues in solanum tuberosum. its ortholog in physalis pubescens, mpf2, is expressed in floral tissues. knock ... | 2005 | 15824316 |
| two p-type atpases are required for copper delivery in arabidopsis thaliana chloroplasts. | copper delivery to the thylakoid lumen protein plastocyanin and the stromal enzyme cu/zn superoxide dismutase in chloroplasts is required for photosynthesis and oxidative stress protection. the copper delivery system in chloroplasts was characterized by analyzing the function of copper transporter genes in arabidopsis thaliana. two mutant alleles were identified of a previously uncharacterized gene, paa2 (for p-type atpase of arabidopsis), which is required for efficient photosynthetic electron ... | 2005 | 15772282 |
| the critical role of disulfide bond formation in protein sorting in the endosperm of rice. | many seed storage proteins, including monomeric 2s albumin and polymeric prolamin, contain conserved sequences in three separate regions, termed a, b, and c, which contain the consensus motifs lxxc, ccxql, and pxxc, respectively. protein-sorting mechanisms in rice (oryza sativa) endosperm were studied with a green fluorescent protein (gfp) fused to different segments of rice alpha-globulin, a monomeric, abc-containing storage protein. the whole abc region together with gfp was efficiently transp ... | 2005 | 15749763 |
| phototropins promote plant growth in response to blue light in low light environments. | phototropins (phot1 and phot2) are plant-specific blue light receptors for phototropism, chloroplast movement, leaf expansion, and stomatal opening. all these responses are thought to optimize photosynthesis by helping to capture light energy efficiently, reduce photodamage, and acquire co2. however, experimental evidence for the promotion of plant growth through phototropins is lacking. here, we report dramatic phototropin-dependent effects on plant growth. when plants of arabidopsis thaliana w ... | 2005 | 15749755 |
| leucine-rich repeat receptor-like kinase1 is a key membrane-bound regulator of abscisic acid early signaling in arabidopsis. | abscisic acid (aba) is important in seed maturation, seed dormancy, stomatal closure, and stress response. many genes that function in aba signal transduction pathways have been identified. however, most important signaling molecules involved in the perception of the aba signal or with aba receptors have not been identified yet. receptor-like kinase1 (rpk1), a leu-rich repeat (lrr) receptor kinase in the plasma membrane, is upregulated by aba in arabidopsis thaliana. here, we show the phenotypes ... | 2005 | 15772289 |
| a minus-end-directed kinesin with plus-end tracking protein activity is involved in spindle morphogenesis. | diverse kinesin motor proteins are involved in spindle function; however, the mechanisms by which they are targeted to specific sites within spindles are not well understood. here, we show that a fusion between yellow fluorescent protein (yfp) and a minus-end-directed kinesin-14 (c-terminal family) from arabidopsis, atk5, localizes to mitotic spindle midzones and regions rich in growing plus-ends within phragmoplasts. notably, in arabidopsis interphase cells, yfp::atk5 localizes to microtubules ... | 2005 | 15659646 |
| protein diversity confers specificity in plasmid segregation. | the parg segregation protein (8.6 kda) of multidrug resistance plasmid tp228 is a homodimeric dna-binding factor. the parg dimer consists of intertwined c-terminal domains that adopt a ribbon-helix-helix architecture and a pair of flexible, unstructured n-terminal tails. a variety of plasmids possess partition loci with similar organizations to that of tp228, but instead of parg homologs, these plasmids specify a diversity of unrelated, but similarly sized, partition proteins. these include the ... | 2005 | 15805511 |
| who owns the data? | about ten years ago, a group of scientists began to argue that it was unfair to ask other scientists to pay to read the results of research that had been publicly funded. | 2005 | 15833127 |
| complete reannotation of the arabidopsis genome: methods, tools, protocols and the final release. | since the initial publication of its complete genome sequence, arabidopsis thaliana has become more important than ever as a model for plant research. however, the initial genome annotation was submitted by multiple centers using inconsistent methods, making the data difficult to use for many applications. | 2005 | 15784138 |
| structure-function analysis of cf-9, a receptor-like protein with extracytoplasmic leucine-rich repeats. | the tomato (lycopersicon pimpinellifolium) resistance protein cf-9 belongs to a large class of plant proteins with extracytoplasmic leu-rich repeats (elrrs). elrr proteins play key roles in plant defense and development, mainly as receptor-like proteins or receptor-like kinases, conferring recognition of various pathogen molecules and plant hormones. we report here a large-scale structure-function analysis of an elrr protein. a total of 66 site-directed mutants of cf-9 were analyzed for activity ... | 2005 | 15722474 |
| the cotton actin1 gene is functionally expressed in fibers and participates in fiber elongation. | single-celled cotton fiber (gossypium hirsutum) provides a unique experimental system to study cell elongation. to investigate the role of the actin cytoskeleton during fiber development, 15 g. hirsutum actin (ghact) cdna clones were characterized. rna gel blot and real-time rt-pcr analysis revealed that ghact genes are differentially expressed in different tissues and can be classified into four groups. one group, represented by ghact1, is expressed predominantly in fiber cells and was studied ... | 2005 | 15722467 |
| light regulates cop1-mediated degradation of hfr1, a transcription factor essential for light signaling in arabidopsis. | arabidopsis thaliana seedlings undergo photomorphogenesis in the light and etiolation in the dark. long hypocotyl in far-red 1 (hfr1), a basic helix-loop-helix transcription factor, is required for both phytochrome a-mediated far-red and cryptochrome 1-mediated blue light signaling. here, we report that hfr1 is a short-lived protein in darkness and is degraded through a 26s proteasome-dependent pathway. light, irrespective of its quality, enhances hfr1 protein accumulation via promoting its stab ... | 2005 | 15705947 |
| a novel cytochrome p450 is implicated in brassinosteroid biosynthesis via the characterization of a rice dwarf mutant, dwarf11, with reduced seed length. | we have characterized a rice (oryza sativa) dwarf mutant, dwarf11 (d11), that bears seeds of reduced length. to understand the mechanism by which seed length is regulated, the d11 gene was isolated by a map-based cloning method. the gene was found to encode a novel cytochrome p450 (cyp724b1), which showed homology to enzymes involved in brassinosteroid (br) biosynthesis. the dwarf phenotype of d11 mutants was restored by the application of the brassinolide (bl). compared with wild-type plants, t ... | 2005 | 15705958 |
| basic pentacysteine1, a ga binding protein that induces conformational changes in the regulatory region of the homeotic arabidopsis gene seedstick. | the mechanisms for the regulation of homeotic genes are poorly understood in most organisms, including plants. we identified basic pentacysteine1 (bpc1) as a regulator of the homeotic arabidopsis thaliana gene seedstick (stk), which controls ovule identity, and characterized its mechanism of action. a combination of tethered particle motion analysis and electromobility shift assays revealed that bpc1 is able to induce conformational changes by cooperative binding to purine-rich elements present ... | 2005 | 15722463 |
| the arabidopsis gamyb-like genes, myb33 and myb65, are microrna-regulated genes that redundantly facilitate anther development. | the functions of the vast majority of genes encoding r2r3 myb domain proteins remain unknown. the closely related myb33 and myb65 genes of arabidopsis thaliana have high sequence similarity to the barley (hordeum vulgare) gamyb gene. t-dna insertional mutants were isolated for both genes, and a myb33 myb65 double mutant was defective in anther development. in myb33 myb65 anthers, the tapetum undergoes hypertrophy at the pollen mother cell stage, resulting in premeiotic abortion of pollen develop ... | 2005 | 15722475 |
| the potassium transporter athak5 functions in k(+) deprivation-induced high-affinity k(+) uptake and akt1 k(+) channel contribution to k(+) uptake kinetics in arabidopsis roots. | potassium is an important macronutrient and the most abundant cation in plants. because soil mineral conditions can vary, plants must be able to adjust to different nutrient availabilities. here, we used affymetrix genechip microarrays to identify genes responsive to potassium (k(+)) deprivation in roots of mature arabidopsis (arabidopsis thaliana) plants. unexpectedly, only a few genes were changed in their expression level after 6, 48, and 96 h of k(+) starvation even though root k(+) content ... | 2005 | 15734909 |
| differential regulation of flowering locus c expression by vernalization in cabbage and arabidopsis. | vernalization is required to induce flowering in cabbage (brassica oleracea var capitata l.). since flowering locus c (flc) was identified as a major repressor of flowering in the vernalization pathway in arabidopsis (arabidopsis thaliana), two homologs of atflc, boflc3-2 and boflc4-1, were isolated from cabbage to investigate the molecular mechanism of vernalization in cabbage flowering. in addition to the sequence homology, the genomic organization of cabbage flc is similar to that of atflc, e ... | 2005 | 15734903 |
| regulation of secondary cell wall development by cortical microtubules during tracheary element differentiation in arabidopsis cell suspensions. | cortical microtubules participate in the deposition of patterned secondary walls in tracheary element differentiation. in this study, we established a system to induce the differentiation of tracheary elements using a transgenic arabidopsis (arabidopsis thaliana) cell suspension stably expressing a green fluorescent protein-tubulin fusion protein. approximately 30% of the cells differentiated into tracheary elements 96 h after culture in auxin-free media containing 1 mum brassinolide. with this ... | 2005 | 15709154 |
| impact of reduced o-acetylserine(thiol)lyase isoform contents on potato plant metabolism. | plant cysteine (cys) synthesis can occur in three cellular compartments: the chloroplast, cytoplasm, and mitochondrion. cys formation is catalyzed by the enzyme o-acetylserine(thiol)lyase (oastl) using o-acetylserine (oas) and sulfide as substrates. to unravel the function of different isoforms of oastl in cellular metabolism, a transgenic approach was used to down-regulate specifically the plastidial and cytosolic isoforms in potato (solanum tuberosum). this approach resulted in decreased rna, ... | 2005 | 15728339 |
| hfr1 is targeted by cop1 e3 ligase for post-translational proteolysis during phytochrome a signaling. | upon activation by far-red light, phytochrome a signals are transduced through several pathways to promote photomorphogenesis. the cop1 e3 ligase represses photomorphogenesis in part by targeting transcription activators such as laf1 and hy5 for destruction. another positive regulator of photomorphogenesis is hfr1, a basic helix-loop-helix (bhlh) transcription factor. here, we show that hfr1 colocalizes with cop1 in nuclear bodies, and that the hfr1 n-terminal region (amino acids 1-131) interact ... | 2005 | 15741320 |
| a sec14p-nodulin domain phosphatidylinositol transfer protein polarizes membrane growth of arabidopsis thaliana root hairs. | phosphatidylinositol (ptdins) transfer proteins (pitps) regulate signaling interfaces between lipid metabolism and membrane trafficking. herein, we demonstrate that atsfh1p, a member of a large and uncharacterized arabidopsis thaliana sec14p-nodulin domain family, is a pitp that regulates a specific stage in root hair development. atsfh1p localizes along the root hair plasma membrane and is enriched in discrete plasma membrane domains and in the root hair tip cytoplasm. this localization pattern ... | 2005 | 15728190 |
| crystal structure of potato tuber adp-glucose pyrophosphorylase. | adp-glucose pyrophosphorylase catalyzes the first committed and rate-limiting step in starch biosynthesis in plants and glycogen biosynthesis in bacteria. it is the enzymatic site for regulation of storage polysaccharide accumulation in plants and bacteria, being allosterically activated or inhibited by metabolites of energy flux. we report the first atomic resolution structure of adp-glucose pyrophosphorylase. crystals of potato tuber adp-glucose pyrophosphorylase alpha subunit were grown in hi ... | 2005 | 15692569 |